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Char rate and depth
Sizer determines the reduced cross section for fire design by calculating a char depth for each of the sides sides exposed from the notional char depth from B.4.4 using the fire duration you input. Since this method is employed, corner rounding from B.4.5 is not considered.
Fire Protection
Fire duration is reduced by the values given in B.8.1 for the protection method chosen.
Zero strength-layer
The additional reduction in cross section due to the zero-strength layer in B.5.1 is applied.
Design Criteria
Sizer performs shear, axial, bending moment and combined axial and bending design on the fire-reduced section using the same provisions in CSA O86 as those for regular design.
Modification Factors
As per B.3, the factors related to lateral support KL, CC, and KC are calculated using the fire reduced section, size factor KZ is calculated using the full section, duration factor KD factor is for short-term loads regardless of the loads on the member, system factor KH is 1.0, and the resistance factor φ is 1.0 rather than the usual 0.9 or 0.8.
The strength adjustment factor Kfi from B.3.9 is applied to shear, bending, compression and tension strengths.